Cutting machine



Patented Jan. 4, 1927.

UNITED STATES PATENT orricr..

PHILIP S. MIT'IS, OF SAGINAW', MICHIGAN, ASSIGNOR TO MITTS & MERRILL, OF SAGINAVT, MICHIGAN, A CORPORATION F MICHIGAN.

CUTTING ivnfionrnn.Y

Application filed March 19, 1923. Serial No. 626,144.

This invention relates to cutting machines of the kind commonly known as hogs and employed for disintegrating many kinds of materials.

A hog of the kind to which my improvement is especially well adapted consists in a cylindrical knife-carrying drum revolvably mounted in a cylindrical casinghaving an inlet for crude material in one side and i0 an outlet for the disintegrated product on the opposite side, and stationary cutter bars around the lower part of the inner periphery of the casing between the inlet and outlet openings.

The drum nearly lills the chamber of the casing and the knives project only slightly outside the drum rim. Such a hog is illustrated and described in Patent No. 1423867 issued July 25, 1922,

The objects of my invention are, to enable chunks of wood, sheets of veneer and other materials to be cut into small pieces, to take out the material as tast as it is reduced to a predetermined maXi mum size or smaller, to V automatically recut all material that was not sutliciently reduced in its first passage through the machine, and to repeat the cutting operation until all the material fed to the machine emerges therefrom in a state of ineness in which no over-size particles are present. No subsequent screening is, therefore, re uired to remove larffe nieces fromthe product.

A further object is to secure the greatest possible rate of output ot properly cut and sized product per unit time.

A still further object is to so design and arrange the discharge pipe connections that the direction ot movement of the cut material will be changed immediately after leaving the' cutter chamber, thereby checking its velocity and dropping out nails, pieces of iron and other heavy particles that have passed through the machine, while the good material is carried along by the air current into the exhaust :tan or such other disposal apparatus as may be provided.

`With the foregoing and certain other objects in view which will appear later in the specification, my inventioncomprises the devices described and claimed and the equivalents thereor".

In the drawings, Fig. l is a part sectional side view et a liogvembodying my improven ment, l

Fig. 2 is a perspective view of the recutting screen and the air-How chamber as seen from inside the machine.

Fig. 8 is a diagrammatic detail of a section ot the screen.

Fig. l is a perspective view of the machine assembled.

As is clearly shown in the drawings, l is the usual casing ot the hog, 2 the feed opening, 3, 3 is a plurality of stationarycutting bars located around the lower part of the periphery of the casing and't is the dischargev opening. The cylindrical drum 5, which nearly iills the casing, has knives 6 that project slightlyA beyond the cylindrical surface oi3 the drum. The drum is revolvably mounted within the casing.

In the customary operation of such a hog, material is fed into opening 2, passes between the rapidly moving knives G and the successive stationary cutting bars 3 and is discharged through the opening ll. The dis charged materia-l usually consists of a mixture of finely cut andl coarsely cut particles.

My present improvement embodies improved means to screen the material, to automatically recut those pieces which may not have been suiiiciently reduced in Size by the previous passage through theA machine and it automatically repeats the recutting and rescreening operations as many times as may be necessary to reduce the material to the required size.

Material is not permitted to escape from my present machine until it has been reduced to the desired degree ot' fineness. `rVhen that degree ot' iineness has been attained the material is automatically discharged and cleared away from the machine.

l employ a recutting and sizing screen 7 around that part of the drum which is not occupied by the inlet opening 2 and the stationary cutting knives 3. This part usually comprises about one third of the circum- 10 terence of the casing.

.A similar screen 8 is located across the discharge opening 4,

The operation of screens 7 and 8 is as follows:

v'Some ot' the materia-l which entered feed opening Q and passed the knives and stationary cutting bars 8, 3 is projected tangentially oy centrifugal force from the drum knives throng i the screen openings. Other not se well cut, and consequently 1m of large-r size, can not pass 'through and is swept around the inside surface ot screens 7 and 8 like a rapidly moving stream along the thin annular space CS that surrounds the periphery of drum 5. This coarser material is delivered into the inlet hopper 2 Where it is joined by non' supply ot material. The material again encounters .tlie'cutting knives and stationary bars 8, 3 and the action is repeated, the line re-cut material being projected at high speed vdragonally through the openings ot' screens :E3 and The screen lis preferably made ot 'heavy material such steel plate, rigid enough to .retain iltsorifrinal shape .unifier conditions ot' hard service. it is termed with large perfora-tions as shown in Figs. .and 3. VIhese Apert'orations may lbe circular as shown7 or rectangular', -or :the `screen may be built up oft bars.

Cut material is .thrown from the knives tangential'ly and lonly such material can .pass lthrough vthe V'large perito-rations as is :tine enough to go .through the diagonally projected area ol the opening as indicated at A. Fig. 3.

The screen, therefore, serves `as .cylindrical nf'all to guide the coal-ser material rejected by vthe screen around the drum through the .thin channel S and baci; to the :cutter bars 3 toi` recutting. It also .serves as a sizing screen :tor .particles :ot finely .cut material :that are driven against it tangen- :tially and with :great velocity.

I increase :the output et the machine .per unit .time by .eliminating air blast action Within the Working chamber, .as `follows:

The fan or blast-.producing vaction of any knives and drum is slight because the in- :terior of the drun'i chan'iber is .practically air bound, as distinguished from machines in which the revolving ltnit'eecariying cylinder `also acts as 'an air blasit-.producing element.

Aint'annirng by the knives is further minimized by vso arranging the parts that the thin annularchannel or working space 'S vbetween the .outer periphery of the drum and the inner periphery .of the casing is occupied .as fully as Apossible by the out vand ,partly sized niiaterial instead .ot' being occu- .pied,.as heretofore, by a mixture ot `material and air.

Since there is in practice only a negligible amount ot -t'an action inthe casing -there is no great amount of air driven :through the Vpertocra'lions ot my `screen by the revolving drum. Y

In the absence of such an air-blast action through the screen, cut particles are, therefore, projected through the perterations by the momentum imparted lby the rim velocity ot ythe drum instead of being` carried through the .screen by .floating-in .an air blast that has been created by the tanning mill action ot thecutters. as in .machines or' the liind above reterred to.

By making the channel S thin as above described the cut material `-is contincd in a "thin layer between tilre'tlrn'm or linite-carry ing member and the screen. By being confined to a thin layer which travels at high velocity. the `material does not clog the screen openings, as Would be the case if the *layer 'S were thic-lr. The thin -la-yer insures 'that each sepa-rate particle o-f the cut material :shall .more quickly 'haye'an eli-)Apertunity to l'ly out through the holes. It the layer were 'too thick those particles 4nearest the .drum would not have so goed an opportunity to Yescape. Consequently Vby placing 4the vscreen close .to the drum rim and d 'iiing the material :around the screen surface in a ythin .layer the hourly .output ot' the machine .is greatly increased.

The. 'thickness IS. that is. the .radial ydistance t'rom the drum rim .to .the een, is determined in practice by the required sine :ot lfinis-hed particles, the speed votl .the cutknives .and the nature of vthe material, but in any case vmy arrangement by which the V'material is passed .over `the -screen a-l- Ways in a thin layer enables me to adapt the machine to any required conditions, since the drum .rim forms .one confining `Wall for the thin .layer loft material and the .screen .is .the :other wall, the distance Ibetween them being .gauged to .suit :the jparticular condi-tions et .op erati on.

In fpraotioe the projected er tree-flow larea A vof the screen perforation-s ot my machine when Working at full capacity are filled 'by Valmost solid streams otfcut material, instead of :by a mixture ot .material and air. Obviously the capacity of ya hog et gisten size and :speed as :measured in terms ot cubic feet ot cut material passing through a square foot ot' screen surf-ace per unit lof time is there-by enormously increased.

Cut material ,projected tlirough the screen from :the .air-`bound drum preferably picked up vby an indesienden-'t current 'ot air that flows 'around the youtside Iperiphery ot' the screembut vnot through it. To carry this air current I provide an outer casing l() forming an air flow passageway or ljacket ll having yan inlet` 12, .its lower end com-municating with discharge pipe 13.

Air inlet 12 has proper `vr-)hnnetr-ic capacity to supply .the air flow needed tor sweeping the fine vmaterial away from screen 7. To ipreven-t particles'that `have been discharged y"at high velocity through the uppermost `'per-toi'ations of screen '.7 Afrom flying; :upward .out through :inlet l2 I provide baffles l2A and l2B to take the impact et 'the projected particles. The material strikes i. se battles anddrops back into the passage Way ll and is taken by the flow of fair 'as above described.

ilu

rl`he casing with screen 7 and inlet spout 2 may be hinged as at 15 to the frame ot body 1 to afford ready access to the drum knives.

A hog not originally equipped with a recutting and sizing screen 7 may be fitted with such a screen merely by removing' the original plain casing section and substituting the screen and casing as shown in thc drawings. A suitable air current may preferably be produced in pipe 13 by action ol a ian t not shown). Material projected through screen 8 is discharged into suction pipe 13 where it encounters the air currenttrom passageway 11 and is thereby propelled through the discharge pipe 13.

To better regulate the supply ot' air to the discharge pipe 13 I provide a valvecontrolled air inlet 14 at a point close to the discharge outlet et.

This inlet 14 also permits pieces of iron and other heavy material to be dropped out near the point where the direction ot iiow from passageway 11 is changed into discharge pipe13.l A baiiie wall or separating plate 15 is also provided, against which particles-from screen 8 impinge, lose their velocity and drop by gravity into the exhaust pipe 13 where they meet the air current entering at- 1-1, and are lcarried away. It any pieces oit iron and the like are in the cut material they will drop through the air inlet 14 as soon as their velocity is checked by striking baiiie 15.

By the means above described I have produced a recutting and re-screening device that automatically carries partly cut material through the knives repeatedly, as many times as may be necessary to reduce it to the required size and when that size has been attained the material is projected out ot the machine and into an air current generated independently oi the cutting drum. It is projected by its own momentum due to the velocity imparted to it b v the knives in the thin channel S. Its path of flight is tangential to the drum rim and diagonally through the openings in the screen. This air current sweeps over the outside surface ol the screen, but not through it and automatically separates iron and heavy materials and takes the sized product awav from the machine and keeps the screens clear, while greatly increasing the rate of output of the machine.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In a cutting machine including a cylindrical shell, and a substantially cylindrical knife-carrying member revolvable therein, a cylindrical screen forming a wall of said shelL said screen concentric with said knife-carrying member and in close proximity thereto, to form a thin annular channel in advance of each knife, said screen formed with large perforations adapted to permit the free passage diagonally therethrough of cut pieces when thrown by centrifugal torce tangentially from the rim of said knife-carrying drum. l

2. A drum-type cutting machine having a part ot' its casing formed of a screen located concentric with the drum, said screen tormed with large perfor-ations adapted to permit the passage of small particles only when diagonally projected therethrough,` an outer casing enclosing said screen, said outer casing having an air inlet at one end and a suction o-utlet at the other end, and adapted to direct an air current around the outer surface of said screen but not through its perforations.

A regrinding and sizing device for cutting machines including a casing having stationary cutting bars, a knife-carrying drum in said casing, a part ot' the wall of said casing formed of a non-yielding sizing screen having openings therein adapted 'to pass material diagonally therethrough, said screen arranged in close proximity to the path of travel ot' said knives to form a thin channel therebetween, a wall outside said screen and spaced therefrom, the space between said screen and wall comprising an air passageway having a current of air sweeping circumt'erentially around the outside surface only ot' said screen.

4. A cutting hog comprising a casing having a feed opening and a plurality of stationary cutting bars located beneath said opening and around the lower periphery of said casing, a knife-carrying drum revolvable within said casing and concentric with the working edges ot said cutting bars, a discharge pipe, a discharge opening in said casing beyond said cutting bars and communicating with said discharge pipe, an air inlet in said discharge pipe near the discharge opening, an air inlet in the upper side ol said discharge pipe, a screen forming a wall for the ripper' part of said casing, and an air passageway outside of said screen surrounding said screen and communicating with the opening of said discharge pipe,

5. In a machine ot the class described, a. casing have a feed opening and a discharge opening, a screen across said discharge opening, a revolvable cylindrical drum having knives projecting from the periphery thereof, stationary cutting bars tiXed to the lower inner periphery of the casing between said openings, a sizing screen arranged close to the periphery of said drum to form, together with the drum, a thin annular channel through which material being worked is constrained to travel in a thin stream, for the purposes set forth.

In testimony whereof, I aliix my signature.

PHILIP S. MITTS. 

